1. Field of the Invention
The invention pertains to a device with a key-actuatable lock cylinder and with a switching device, which, as a function of the rotation of the key, activates or deactivates certain electrical functions in a motor vehicle or the like, especially an ignition starter switch for a motor vehicle, where the lock cylinder consists of a stationary cylinder housing and a cylinder core, which is supported in the housing with freedom of rotation, which--starting from an original rotational position--is moved by the turning of the key into one of several defined working positions, in which the switching device initiates an electrical function in the motor vehicle or the like, which function is specific to the working position in question; where, in addition to tumblers for blocking the rotation of the cylinder core in the cylinder housing, a key channel to accept the key for unlocking the cylinder core is provided in the interior of the cylinder core; where permanent magnets are provided on the circumference of the cylinder core; and where, in addition to at least one locking channel for the tumblers, sensors responding to the permanent magnets of the cylinder core are also provided in the cylinder housing. The lock cylinder consists of a stationary cylinder housing and a cylinder core supported in the housing with freedom to rotate. The key can be inserted and removed from its key channel only in a certain original rotational position of the cylinder core. By turning the key, the cylinder core can be brought into certain defined rotational positions, which are to be referred in brief below as "working positions". In these working positions, certain electrical functions in the motor vehicle or in some other useful object are activated or deactivated by way of the switching device.
2. Description of the Related Art
When a device such as this is used in motor vehicles, it serves as a so-called "ignition starter switch". In the known device, the switching device has both a contact element which turns along with the turning of the key and stationary contacts, which are connected electrically to the given on-board electrical system. This device is located at the inner end of the lock cylinder. The movable switching element is connected in a torsionally rigid way to the cylinder core. In the working positions, the movable contact element becomes electrically connected to the stationary contact to which the system responsible for the desired function in the motor vehicle is connected. In the case of an ignition starter switch, there are usually three working positions besides the original rotational position. These include a first working position for switching on the electrical system of the vehicle, a second working position for releasing the internal combustion engine present in the vehicle for ignition, and a third working position for starting the engine.
The switching device in the known device occupies a considerable amount of space, and the space it occupies is then no longer available for other important components of the motor vehicle. In the known ignition starter switch, the switching device is installed at inner end of the lock cylinder. Thus the ignition starter switch is usually installed near the steering column of the motor vehicle, where it also has other duties to fulfill. These include the locking of the steering column after the key has been removed. Problems are encountered when the elements of the switching device are contacted mechanically. The angular distances between the working positions of the cylinder core initiating the various functions can be very small, for which reason the distances between the contacts in the switching device can be distinguished reliably only when a sufficient amount of space is available in the radial direction for the movement of the movable switching element from one angular position to the other. In addition, for safety reasons alone, a minimum amount of space must be provided for the switching device. All of this increases the space requirement.
There are locks (U.S. Pat. No. 5,186,031) in which a permanent magnet is installed on the circumference of the cylinder core. When the cylinder is turned by the key, an electronic monitoring function takes place by way of a sensor integrated into the cylinder housing; this sensor responds to the magnetic field of the cylinder core turning past it. As a result, the electrical system of the motor vehicle is turned on, and only then can the above-described switching device be activated. If the lock cylinder is forcibly torn out, electrical manipulations of the contacts are therefore useless. Unless the switching device is activated by way of the permanent magnet, which must be moved past the sensor, the switching device remains off-line. It therefore did not appear that there was any way to reduce the space requirement in the design of the known device.
In another device (U.S. Pat. No. 5,455,571), the attempt was made to make it more difficult for unauthorized persons to read the activation signal. This attempt took the form of a second sensor, which acts on the signal output of the addressed first sensor. The goal of this measure was to prevent outsiders from determining the signal value.